Production of a high-porosity refractory

Claim 1

PROCESS OF PRODUCING A REFRACTORY MAGNESIUM OXIDE PARTICLE COMPRISING INTRODUCING BRINE DERIVED MAGNESIUM HYDROXIDE INTO A ROTARY HEATING ZONE, SAID ROTARY HEATING ZONE HAVING A CONSTRICTION THEREIN, HEATING SAID MAGNESIUM HYDROXIDE TO A TEMPERATURE OF FROM ABOUT 450-900*C. TO FORM IMAGNESIUM OXIDE PARTICLES, PASSING SAID MAGNESIUM OXIDE PARTICLES INTO A MILLING AND AGGLOMERATING ZONE WITHIN SAID KILN, SAID MILLING AND AGGLOMERATING ZONE BEING FORMED BY THE HOLD-UP OF MAGNESIUM OXIDE PARTICLES BY SAID CONSTRICTION WITHIN SAID ROTARY HEATING ZONE, CRUSHING SAID MAGNESIUM OXIDE PARTICLES AND AGGLOMERATING THE CRUSHED MAGNESIUM OXIDE PARTICLES INTO POROUS BALLS OF MAGNESIUM OXIDE HAVING A SILICA CONTENT NOT ABOVE 4% AND A CRYSTALLITE SIZE OF FROM ABOUT 1-40 MICRONS WITHIN SAID MILLING AND AGGLOMERATING ZONE, SAID AGGLOMERATING OF THE CRUSHED MAGNESIUM OXIDE PARTICLES BEING CARRIED OUT AT TEMPERATURES OF FROM ABOUT 9001050*C., SINTERING SAID MAGNESIUM OXIDE POROUS BALLS AT TEMPERATURES OF FROM ABOUT 1600-1800*C. AND RECOVERING MAGNESIUM OXIDE PARTICLES HAVING AN OPEN POROSITY OF FROM ABOUT 25-50%, SAID POROSITY BEING FORMED BY PORES SUBSTANTIALLY ALL OF WHICH HAVE AN EFFECTIVE DIAMETER ABOVE ABOUT 5 MICRONS.